.banner{
  position: relative;
  height: 480px;
}
.banner .banner_img{
  height: 480px;
  background: pink;
}

.banner .banner_img .banner_sider{
  position: absolute;
  left: 180px;
  right: 855px;
  width: 244px;
  height:480px;
  background-color: rgba(232, 220, 250, 0.7);
}

.banner .banner_img .banner_sider ul li{
  height: 60px;
  padding: 0 0 0 30px;
  line-height: 60px;
}
.banner .banner_img .banner_sider ul li:hover{
  background: #7e7e7e;
  cursor: pointer;
}
.banner .banner_img img{
  width: 100%;
  height: 100%;
}
.banner .banner_img span{
  position: absolute;
  top: 240px;
  display: block;
  width: 10px;
  height: 18px;
  background:url(../images/banner_arrow_left.png) no-repeat 0 0;
  background-size: 100%;
}
.banner .banner_img span.banner_btn_left{
  left: 450px;
}
.banner .banner_img span.banner_btn_right {
  position: absolute;
  top: 240px;
  right: 250px;
  background: url(../images/banner_arrow_right.png) no-repeat 0 0;
  background-size: 100%;
}